Based on the construction of the Yongan geomagnetic station, introduce some methods of the field selection、the building programs、the choice of materials and testing, magnetic field gradient monitoring during the congstruction of the Yongan geomagnetic station .The practice shows that The Survey selected and the construction of the Yongan geomagnetic station can satisfy the technical requirement of construction specification of geomagnetic station,which proves these methods are valid, and can be used for reference of geonagnetic station construction later.